How to get all the predefined do_action() calls from an active theme

Question

To hook my plugin content into anywhere, suppose I offered the theme developers to create their own hooks with a prefix (pre_) anywhere in their theme - the rest of the hook is unknown to me. So what will they do?

Suppose, in single.php they placed a hook like:

do_action( 'pre_kauwa' );

in page.php they placed a hook like:

do_action( 'pre_kala' );

And so on...

How can I get all those do_action() declarations with a prefix pre_ from an active WordPress installation (active theme)
or,
from an active WordPress viewport (post, page, archive bla bla)

...so that I can make a list of hooks dynamically where my content can be hooked using add_action()?

Testing testing...

In wp-includes/plugin.php I found the has_filter() function declaration. From there I took the following line for testing:

$wp_filter = $GLOBALS['wp_filter'];
$has = ! empty( $wp_filter[ $tag ] );

In my dummy theme's index.php after the_content() (within the loop) I placed:

do_action( 'pre_kk' );

Just after the do_action() call I placed:

$t_test = $GLOBALS['wp_filter'];
$hk = 'pre_kk';
var_dump( $t_test[$hk] );

But it's throwing an undefined index.

Answer 1

pre_ is a terrible prefix for this because it's going to interfere with all of the WordPress internal hooks that are prefixed with pre_.

But if you want to get the name of all the actions and filters called on a certain page you can use the all hook which adds your callback to every hook. Obviously this is terribly expensive so you wouldn't want to do it on a production server.

add_action( 'all', 'wpse_all_actions' );
function wpse_all_actions() {
  static $pre = [];
  $filter = current_filter();
  if( 'pre_' === substr( $filter, 0, 4 ) ) {
    $pre[] = $filter;
  }
  if( 'shutdown' === $filter ) {
    var_dump( $pre );
  }
}